1899.] THE MYOLOGY OP THE EDENTATA. 329 



Biceps. — Among the Bradypodidce, Bradypus is remarkable for 

 possessing a humeral head. This was noticed ia five specimens 

 (1, 2, 3, 4, 5), and is described under that name by all five 

 observers individually. In all these cases the head was large, and 

 in all the insertion of the muscle was much blended with that of 

 the brachialis anticus. We must confess that we find it very 

 difficult to give any general rule for determining when a slip 

 coming from the anterior aspect of the humerus and more or less 

 connected with both brachialis anticus and biceps should be 

 regarded as a brachialis anticus internus and when a humeral head 

 of the biceps. When the connection is only with one muscle, as 

 is sometimes the case, the task is comparatively simple. We are 

 not, in this instance, prepared to take a different line from the 

 above-mentioned writers, and therefore, at least conditionally, adopt 

 their terminology. In all the five animals above alluded to there 

 was also a glenoid head, and one (2) in addition possessed a 

 coracoid head, which went to the fascia on the inner side of the 

 forearm. The combined gleno-humeral muscle may be inserted 

 into the radius or the ulna or both. In Cholcepus (8, 10) only the 

 glenoid head is present, and is inserted partly into the radius 

 partly into the ulna. In one specimen (8) part of the muscle 

 joined the acromial deltoid. In the Miirmecopliayidce, Myrmeco- 

 phaga (11) has glenoid and coracoid heads, the latter rising from 

 the position which would be occupied by the coracoid process were 

 it present; the glenoid or long head divides below, the more 

 superficial fibres being inserted into the radius with the short head, 

 whilst the deeper group join the brachialis anticus to be inserted 

 into the ulna. The description which we have of the other two 

 specimens (12, 13) seems to agree fairly accurately with the above. 

 Tamandua (14, 15, 16) resembles Myrmecophaga, though Happ 

 describes a humeral head in addition, which we believe, in this 

 case, is a part of the brachialis anticus. In Cycloihurus (17, 18, 

 19, 20, 21) only the glenoid origin is present and inserted into the 

 radius and ulna, usually with the brachialis anticus. In the 

 Dasypodidce two heads were present in four specimens (22, 23, 24, 

 and an extra specimen) out of five recorded. In Tatusia (25, 26) 

 and Chlamydopliorus (27) only the long head is present. In the 

 Manidce. the gleno-ulnar part of the muscle alone is present (29, 

 30, 31, 32, 33, 34). In Orycteropus (35, 36, 37) the long head 

 appears to be the only part represented. 



BracMalis anticus. — In the Bradypodidce the outer part of the 

 muscle alone is usually present, and does not in all cases reach as 

 high as the surgical neck of the humerus. It may or may not 

 join the biceps before its insertion, which is into the radius or 

 ulna or both. In our specimen of Bradypus (1) there was also 

 an inner head, which was almost continuous with the coraco- 

 brachialis. In the Myrmecophagidce the muscle is remarkable for 

 its frequent fusion with the bicsps. We can definitely state that 

 in this family the generalized mammalian brachialis anticus rising 

 from the back of the surgical neck of the humerus and winding round 



